FIG. 1 is a flow chart depicting a conventional method 10 for fabricating a conventional perpendicular magnetic recording (PMR) transducer. For simplicity, some steps are omitted. An intermediate layer, chemical mechanical planarization (CMP) stop layer and hard mask layer are provided, via step 12. The intermediate layer is typically aluminum oxide. The CMP stop layer may include Ru, while the hard mask layer may include NiCr. A photoresist mask is provided on the hard mask layer, via step 14. The photoresist mask includes an aperture above the portion of the intermediate layer in which the PMR pole is to be formed. A conventional aperture is formed in the hard mask layer 58 using a conventional ion milling process, via step 16. Step 16 also includes forming a conventional aperture in the CMP stop layer. Thus, through ion milling in step 16, the pattern of the photoresist mask is transferred to both the hard mask and the CMP stop layer in a conventional manner.
Using the hard mask and photoresist mask, a trench is formed in the aluminum oxide layer, via step 18. Step 18 is typically performed using an alumina reactive ion etch (RIE). The top of the trench 66 is desired to be wider than the trench bottom. In addition, the trench may extend through the aluminum oxide intermediate layer. As a result, the PMR pole formed therein will have its top surface wider than its bottom. Consequently, the sidewalls of the PMR pole will have a reverse angle. The conventional PMR pole materials are deposited, via step 20. A chemical mechanical planarization (CMP) is then performed, via step 22. The write gap is provided in step 24. Fabrication may then be completed in step 26. For example, a top shield may be provided.
Although the conventional method 10 may provide the conventional PMR transducer, there may be drawbacks. In particular, the conventional PMR pole may be subject to nonuniformities. The conventional apertures formed in the hard mask and CMP stop layers may not be symmetric. In addition, fencing from redeposition of the NiCr hard mask may exacerbate asymmetries in the hard mask. Consequently, the trench in the aluminum oxide layer and the sidewalls of the conventional PMR pole may not be symmetric. Thus, there may be variations in the critical dimensions of the PMR pole. Such variations may adversely affect the performance of the conventional PMR transducer. Thus, performance of the conventional PMR transducers 50 may be adversely affected.
Accordingly, what is needed is an improved method for fabricating a PMR transducer.